Root-pin for model-teeth



Sept. 16; 1969 w. KLEINER 3,466,751

ROOT -PIN FOR MODEL-TEETH Filed Aug. 7, 1967 INVENTOR. h/az/ 40m? nrrunz/s United States Patent O 3,466,751 ROOT-PIN FOR MODEL-TEETH WillyKleiner, Dental Laboratorium Fischmarktplatz 9, 8640 Rapperswil, St.Gall, Switzerland Filed Aug. 7, 1967, Ser. No. 658,789 Claims priority,application Switzerland, Aug. 9, 1966, 11,702/66 Int. Cl. A610 3/00 US.CI. 3240 7 Claims ABSTRACT OF THE DISCLOSURE A root-pin defined by afrustum, a central hollow space and an annular external groove adjacenta large end of the frustum. A fiat exterior surface is positionedadjacent the smaller end of the frustum and parallel to an axis thereof.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates to a root-pin for a model-tooth die, which pin can be adopted asa help when making indirect inlays, cast crowns, bridges, cast clamps,etc.

Description of the prior art Before root-pins became known, acopper-ring molded impression for instance was filled with cement,amalgam or synthetic resin and the artificial root was simply shapedapproximately by hand or with instruments. Consequently, there werealways slight errors with respect to the fit in the gypsum model.Especially if the root was formed circular, errors in rotation up to 180degrees often occurred. In addition, the roots shaped by hand werecomparatively rough on the surface.

In order to obviate errors in fit and to obtain a smooth surface,root-pins made of synthetic material have recently been created ofhollow shape and square shaped. These known root-pins, however, involvethe drawback that, when filled with quick-curing synthetic resin, theycan be used once only, since the synthetic-resin filling forms anindissoluble combination with the synthetic resin of the root-pin; inthe case of this drawback of being able to be used only once, the highcost of the tools (metal dies) required for making the root-pin plays adecisive part. Further, the synthetic root-pin that can be used onlyonce makes it necessary to keep a very big stock.

These drawbacks shall be avoided through the present invention.

SUMMARY OF THE INVENTION Briefly, a root-pin for model-teeth, whichforms the object of this invention, is characterized by a metal frustumwhich, in the neighborhood of the end with the big diameter, has acentral hollow space of circular cross-section and also one or severaltransverse external annular grooves, and is provided on the outside witha fiat ground surface parallel to the axis and extending from the endwith the small diameter to at least the middle of the length of thefrustum, the distance of said surface from the axis of the frustum beingat least approximately equal to the small radius of the frustum.

BRIEF DESCRIPTION OF THE DRAWING The accompanying drawing shows by wayof example two forms of embodiment incorporating the invention.

FIGURE 1 is a side view, partly in section, of a first embodiment of thepresent invention;

FIGURE 2 is a top view of the form shown in FIGURE 1; and

3,466,751 Patented Sept. 16, 1969 FIGURE 3 is a side view, partly insection, of a second embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGURES 1 and 2,the root-pin shown comprises a metal frustum 1, its big diameter beingdesignated D, its small diameter a, and its length L. In theneighborhood of the end with the big diameter D, the metal frustum 1 hasa central hollow space 2 in the shape of a cylindrical boring, whichextends over about one-third of the length L of the frustum. In additionto that, the metal frustum 1 has two external transverse grooves 3 inthe neighborhood of the same end; the profile cross-section of saidtransverse grooves is a square, one side of which runs parallel to thefrustum axis A-A. On its outside the metal frustum 1 is provided with aflat-ground surface 4 which is parallel to the axis and extends from theend with the small diameter d over about two-thirds of the frustumlength L; the distance of said surface 4 from the frustum-axis AAcorresponds to the small radius r of the metal frustum 1. After thecentral hollow space 2 there follows a coaxial cylindrical blind-boring5, whose diameter is less than that of the central hollow space 2, andwhose axial length is less than that of the central hollow space 2.

At the wider front-end of the metal frustum there are provided twogrooves 6 similar to screw-slots having for their duty to preventrotation of the synthetic resin or of the cement in the hollow frustum1.

Since the frustum 1 is constructed of metal-and brass has been found tobe particularly suitable in this case-the advantage of an unchanging fitin the gypsum impression is obtained, so that an accurate modeling ispossible especially in conjunction with the flat-ground surface 4, sincethe distances to the opposite tooth remain always constant and sourcesof error are practically entirely eliminated.

A further merit of the metal pin is seen in that in the neighborhood ofthe central hollow space 2, the wall thickness W can be kept muchsmaller than in the case of a root-pin made of synthetic material, inaccordance with the lesser deformability of metal as compared with asynthetic material.

Since the metal of the root-pin does not combine chemically with asynthetic-resin filling, the root-pin may always be used again, so thatthe amount kept in stock can be considerably reduced.

The outer transverse grooves 3, which may of course have another profilecross-section than that illustrated, perrnit an appreciably improvedholding of the connecting material between copper-ring impression androot-pin.

As apparent from the second form according to FIG- URE 3, both thecentral hollow space 2 and the blindboring 5 may be made tapering, andthen it will be found more suitable to choose the same angle of taper asused for the metal-frustum 1.

What I claim is:

1. A root-pin for a model-tooth die comprising a metal frustum which, inthe neighborhood of an end having a larger diameter, has a centralhollow space of a circular cross-section, and is provided on the outsidewith a flat-ground surface parallel to an axis of the frustum and whichextends from an end having a smaller diameter to at least the middle ofthe length of the frustum, the distance of said surface from the axis ofthe frustum being substantially equal to the small radius of thefrustum, the central hollow space extending from the larger end towardthe smaller end and terminating short of the smaller end to form a blindopening.

3 '4 2. a root-pin as claimed in claim 1, wherein the cen-, 6. Aroot-pin as claimed in claim 1, including an tral hollow space extendsover approximately one-third transverse groove having a Square ProfileCrossof the length of the frustum. SectlOH- 7. A root-pin as claimed inclaim 1, wherein the metal 3. A root-pin as claimed 1n clarrn 1, whereinafter the frustum is constructed of brass.

central hollow space there follows a coaxial cylindrical 5 blind bore,whose diameter at a place of transition is less References Cited thanthat of the central hollow space, and whose axial U I STATES PA lengthis less than that of the central hollow space. 3 153 283 10/1964Weissman 32 40 4. A root-pin as claimed in claim 1, wherein the cen- 10tral hollow space has a cylindrical shape.

5. A root-pin as claimed in claim 3, wherein the blind 579504 Germanybore and the central hollow space have a cylindrical 584317 Germanyshape. ROBERT PESHOCK, Primary Examiner FOREIGN PATENTS

